c - is there a way to restrict user to input only numerical values for the variables? -

#include<stdio.h>  void main(void) {        int n1,n2,r; // variables      //this add n1 , n2 , shows result, want     // allow numbers not alphabet     printf("enter first number = ");     scanf("%d",& n1);     fflush(stdin);     printf("enter second number = ");     scanf("%d",& n2);     fflush(stdin);     r=n1+n2;     printf("total = %d ", r); } 

as can see codes wont restrict anything, want in restricting input of alphabets

i believe below question answers yours. let me know if helps!

it using while loop ensure input numbers, bee altered chars. can set variable numbers such double or integer, same way can make string.

original answered link: how make cin take numbers

from jesse good's answer

i use std::getline , std::string read whole line , break out of loop when can convert entire line double.

#include <string> #include <sstream>  int main() {     std::string line;     double d;     while (std::getline(std::cin, line))     {         std::stringstream ss(line);         if (ss >> d)         {             if (ss.eof())             {   // success                 break;             }         }         std::cout << "error!" << std::endl;     }     std::cout << "finally: " << d << std::endl; } 

hope helps!